The original 'Alien' trilogy is considered among the best in sci-fi horror. The video game counterparts have not fared nearly as well.

Borderlands studio Gearbox Software and publisher Sega hope to change that with the release of Aliens: Colonial Marines. At its best, this first-person shooter invokes fear and dread in players, but is hampered by inconsistency and outdated visuals.

The events of Colonial Marines take place soon after the original Alien film trilogy, as players investigate the disappearance of the crew of the U.S.S. Sulaco. Classic locations from the series such as LV 426 and Hadley's Hope appear in the game, as players try to root out Xenomorphs, alien parasites known to strike from the shadows.

Colonial Marines is primarily an action game with elements of horror, as Xenomorphs lurk inside vents above and below ground, crawl along walls and ceilings waiting to pounce. The action is often frightening and even a bit stressful, so long as the Xenomorphs are the primary target. Once human opponents -- guards of the evil Weyland-Yutani corporation -- enter play, the action can feel underwhelming.

Players come equipped with a small arsenal ranging from submachine guns to battle rifles, toggling between a primary and secondary weapon. There's also a selection of pistols and explosive devices such as grenades and firebombs. During the campaign, players gain experience and march up the ranks, unlocking attachments including suppressors and scopes to bolster firearms. Each weapon also a secondary fire option, allowing players to shoot incendiary rounds, grenades or other projectiles.

Environments range from tight quarters inside spaceships or buildings to open landscapes, all boasting a murky atmosphere. Unfortunately, what's equally scary are the game's graphics. They're reminiscent of a highly polished title from the PlayStation 2 era. When rain pours, beads of water on the screen are replaced by small, clear streaks that should resemble a liquid substance. Explosions carry little pop, represented by a tiny cloud of smoke before quickly dissipating. On looks alone, it's hard to believe this is a video game for a modern PC or video game console.

The game's audio helps to compensate for the lack of visual quality. Cues such as the beep of a motion sensor or grumble of an alien combine with a powerful soundtrack to heighten the tension.

Playing on the Hardened difficulty (a step above Normal) Colonial Marines' campaign is fun, but definitely inconsistent. The stars are the Xenomorphs, who are quick, cunning and relentless in their pursuit of players. Fights in close quarters where a seemingly endless stream of Xenomorphs creeps through serve as some of the game's most intense scenarios.

The encounters with human opponents are nowhere near as interesting. At times, they resemble a bland first-person shooter, a series of annoying chores players must push through to get to the more gripping battles with Xenomorphs. Most fights involve waiting for a guard to pop his head up from cover to finish them off.

The campaign can be completed alone or cooperatively with friends online. There's also an intriguing multiplayer component that pits Xenomorphs against Marines in challenges such as Team Deathmatch. Similar to the hit zombie franchise Left 4 Dead, teams take turns as aliens or humans, battling to achieve the best score. A Survival mode requires players to band together to tackle wave after wave of Xenomorph.

Aliens: Colonial Marines has moments where it seems a strong horror title might shine through. However, it works better as a weekend rental thanks to an uneven campaign and rough exterior.